1. Field of the Invention
The present invention relates to a dishwasher and a method of controlling the same, and more particularly, to a method of controlling supply and drain of washing water in a dishwasher.
2. Discussion of the Related Art
Dishwashers are electric home appliances for kitchens, which separate residue of food, such as grains of boiled rice, from dishes using high-pressure washing water, and thus, wash the dishes.
In general, a dishwasher includes a main body forming an external appearance of the dishwasher, a washing tub provided in the main body to form a washing space, a sump provided under the washing tub to supply and collect washing water, and spray arms to spray the washing water supplied from the sump to dishes.
The sump includes a water supply channel and a water supply valve to supply the washing water to the sump, a drain channel and a drain pump to drain the washing water in the sump, a pump to supply the washing water stored in the sump to the spray arms at a designated pressure, and a heater to heat the washing water stored in the sump.
An air guide to maintain the pressure in a washing tub and the external pressure equally is provided in an washing tub, and a water level sensor to sense a level of the washing water stored in the sump is provided in the sump.
Hereinafter, supply and drain of washing water in the above-described dishwasher will be described.
First, washing water is supplied to the sump of the dishwasher through the water supply channel and the water supply valve, and when the washing water reaches a designated level in the sump, the supply of the washing water is stopped.
After the completion of the supplying of the washing water to the sump, the pump is operated, and thus, pumps the washing water in the sump to the spray arms, and the spray arms spray the washing water onto dishes located in the washing tub to perform a washing cycle (or a rinsing cycle).
When the washing cycle has been completed, the washing water used in the washing cycle is drained to the outside of the dishwasher through the drain channel and the drain pump. Then, the drained washing water level is sensed by the water level sensor.
When the water level sensor senses that the washing water has been completely drained from the sump, the drain pump is further driven for a designated time to drain any remaining washing water, which has not been sensed by the water level sensor, and then is stopped.
In order to perform an additional washing cycle or rinsing cycle, the washing water is supplied again to the sump. This process may be repeatedly performed during dish washing (or a rinsing cycle).
While the drain of the washing water is converted into the supply of the washing water, as described above, the supplied washing water may be continuously drained through the drain channel.
For example, during the supply of the washing water, power supplied to the drain pump is cut off. However, the washing water supplied to the sump is drained through the drain channel due to inertial operation of the drain pump, which was operated during the draining of the washing water.
Further, in a case that an end terminal of the drain channel is located at a position lower than a level of the washing water in the sump, the washing water supplied to the sump may be continuously drained due to the above-described drain action caused by the inertial operation of the drain pump and a siphon action generated between the sump and the drain channel.
In a case that a part of the washing water supplied to the sump is drained through the drain channel, as described above, the washing water supplied to the sump is insufficient, and thus, a washing (or rinsing) efficiency is lowered.
Further, in a case that the washing (or rinsing) cycle is performed under a condition that the washing water is excessively insufficient, an excessively high load is applied to the pump pumping the washing water to the spray arms and the heater heating the washing water, and thus, components of the dishwasher may be damaged.